Eighteen-year-old Annaleigh Thaumas is the protagonist of House of Salt and Sorrows, with the novel following her first-person perspective. Annaleigh is empathetic, intelligent, and determined to investigate her eldest sister Eulalie’s potential murder. She often assists other characters with their conflicts, such as tending to her pregnant stepmother, Morella; comforting her older sister Camille when she laments her lack of suitors; sleeping with her younger sister Lenore after her fellow triplets die; and protecting her youngest sister Verity from Kosamaras, Harbinger of Madness and Nightmares. While kind, she knows how to take control of difficult situations, like the Churning Festival feast, which makes her sisters, even Camille, look to her for guidance.

As Annaleigh investigates Eulalie’s death and their family’s potential curse, she finds allies in childhood friend Fisher and handsome stranger Cassius—the latter of whom becomes her love interest. Despite being logical and partially because she is logical, she finds herself doubting Verity’s talk of ghosts and accusing Cassius of being her sisters’ killer due to Kosamaras’s illusions. However, she learns to trust Cassius and think through difficult situations in which others distrust her, reinforcing her fortitude and seeing to her happy ending as overseer of the lighthouse, Old Maude.